1. Field of the Invention
The present invention relates to a liquid crystal display device and electronic equipment having an organic film as a planarizing layer.
2. Description of the Related Art
Liquid crystal display devices have found application in a wide variety of electronic equipment thanks to their slimness and low power consumption. Among examples of electronic equipment using a liquid crystal display device are laptop personal computers, display devices of car navigators, personal digital assistants or PDAs, mobile phones, digital cameras and video camcorders.
FIGS. 1A to 1C are views illustrating the configuration of a typical liquid crystal display device. FIG. 1A is a sectional view of the device structure. FIG. 1B is a plan view of a TFT (thin film transistor) substrate. FIG. 1C is a plan view of an opposed substrate.
A liquid crystal display device 1 includes an array substrate (substrate having active elements formed thereon) 2, an opposed substrate 3 and a liquid crystal layer 4. The opposed substrate 3 is a transparent substrate disposed to be opposed to the array substrate 2. The liquid crystal layer 4 is disposed between the substrates 2 and 3.
Pixels, each including a transparent electrode (pixel electrode) 21 and thin film transistor (TFT) 22, are arranged in a matrix form on the array substrate 2 to form a pixel area PXLA. The transparent electrode 21 applies a voltage to the liquid crystal. The thin film transistor 22 selects the transparent electrode 21.
To reduce the height differences on the thin film transistors 22, a planarizing layer 23 is formed between the thin film transistor 22 and transparent electrode 21 on the array substrate 2. The planarizing layer 23 includes an organic film.
A color filter section 31 is formed on the opposed substrate 3. The color filter section 31 includes, for example, black (BK), red (R), green (G) and blue (B) color filters associated with pixels PXL of the array substrate 2. A planarizing layer 32 is formed to reduce the height differences on the color filter section 31. The planarizing layer 32 includes an organic film.
On the side of the planarizing layer 32 facing the liquid crystal layer 4 is formed a transparent electrode 33 adapted to apply a voltage to the liquid crystal.
Further, a sealing area 5 is formed around the pixel area PXLA in which the pixels PXL are formed. The sealing area 5 is formed to hold the array and opposed substrates 2 and 3 together and to fill the liquid crystal.
As described above, structures such as metal wirings 24 including array drive terminals, transistor 22 and transparent electrode (transparent conductive film) 21 are provided on one of the two substrates opposed to each other, namely, the array substrate 24, in the typical liquid crystal display device 1. On the other hand, structures such as the color filters adapted to display an image in color are provided on the opposed substrate 3.
These structures produce height differences on the topmost surfaces of the substrates. This changes the distance between the substrates sandwiching the liquid crystal across their surfaces, thus resulting in a deviation of some optical characteristics of the liquid crystal pixels and degradation in image quality such as contrast.
To prevent these problems, the planarizing layers, each including an organic layer, are formed over the substrates so as to smooth out the height differences resulting, for example, from the wirings.
Further, the liquid crystal display device can provide improved intrasurface uniformity in optical characteristics if the organic films are extended beyond the sealing area adapted to hold the two substrates of the liquid crystal display device together and keep the liquid crystal trapped in the display device.